There are many instances in which a part is moved to a selected position but which position is not easily maintained because of forces tending to cause the part to move out of that position. One such example is the gate in a flow-control system where the gate is, for example, hydraulically moved to an open position from which it often tends to drift back to a closed or partly closed position. Various forms of locks and equivalent retainers have been provided for eliminating this problem, but none has been completely acceptable when considering the factors of original cost, maintenance, reliability and integrity. The locking device most commonly used today in this case is called the semi-automatic gate hanger. It is a purely mechanical device and, as is the case with other mechanical locking devices, it must be reset after each operation by means of a secondary operation: that of releasing a lever and spring and then resetting the same.
According to the present invention, in a preferred form, a novel releasable lock mechanism has been incorporated in a compact unit made up of relatively few working parts for the closing and opening of a pair of complementary jaws capable of gripping and releasing a movable part, such as the operator, for example, connected to a gate control of the character just mentioned. It is a feature of the invention to employ biased elements operative to function in its lock and release modes by selected travel of the part or operator to be controlled.
Further features and advantages will become apparent as a preferred embodiment of the invention is disclosed in detail herein in conjunction with the accompanying sheets of drawings.